20 General utilities library [utilities]

20.18 Execution policies [execpol]

20.18.4 Sequenced execution policy [execpol.seq]

class execution::sequenced_policy { unspecified };
The class execution​::​sequenced_­policy is an execution policy type used as a unique type to disambiguate parallel algorithm overloading and require that a parallel algorithm's execution may not be parallelized.
During the execution of a parallel algorithm with the execution​::​sequenced_­policy policy, if the invocation of an element access function exits via an uncaught exception, terminate() is called.